Intraparticle Modeling of Non-Uniform Active Phase Distribution Catalyst

Abstract

To maximize the performances of heterogeneous catalytic reactors, it is necessary to consider many parameters. Catalytic particle morphology (dimension, shape, active phase distribution) is generally previously established and seldom considered in the optimization of the catalyst to be specific for a given process. In this work, the influence of active phase distribution within spherical catalytic particles (egg-shell, egg-yolk and egg-white), on the yield and selectivity of a product is shown for a consecutive reaction network; here, the intermediate component is the main product of interest. Intraparticle mass and energy balances under non-steady conditions were implemented. Sensitivity studies lead to the identification of the optimal conditions, thus maximizing the yield of the intermediate for each active phase distribution. It was demonstrated that the egg-shell catalyst can maximize the intermediate yield, with a lower active-phase usage.

Intraparticle Model for Non-Uniform Active Phase Distribution Catalysts in a Batch Reactor

“…Under dynamic conditions, two mass balance equations, for the liquid and solid phases have been developed (5) and (6) [5,10]:…”

“…Starting from a standard simulation, obtained by selecting a set of parameters that could well describe the reactive process, the subsequent simulations were performed by decreasing and increasing (lower and higher value, respectively) every single coefficient significantly influencing the reaction environment. Parameters were set taking inspiration, as in our previous work [5], by the physico-chemical properties of the components involved in the catalytic reaction of synthesis of ethylene oxide [5,6]. The coefficients used for the standard simulation are shown in Table 1.…”

“…Several models were reported in the literature, based on simplified approaches, either neglecting the dynamic term [9] or oversimplifying the fluid-solid and intraparticle phases [6], leading in every case to a rough estimation of the concentration and temperature profiles. Insights on the NUD experimental and modelling cases is reported in our previous publication [5].…”

“…Typically, the catalytically active phase is dispersed on a support, which leads to an increase of the specific contact area. It was demonstrated that by confining the active phase in specific portions of the support can lead to high benefits in optimizing the yield of an intermediate, gaining better results compared to the ones obtainable with a uniform active phase distribution, which classically could lead to higher mass transfer limitation, such that the inner part of the catalyst could be hardly reached by the reactants by diffusion, thus a worse catalyst optimization [5,6].…”

“…The latest approach, published by us recently [5], allowed to develop a rigorous Non-Uniform active phase Distribution model (NUD) for a single particle. The results allowed to demonstrate that dependently on the kinetics of a chemical reaction, it is possible to design different NUD of a catalyst allowing the optimization of the yield of a desired chemical intermediate.…”